1. Technical Field
This invention relates to a method for cleaning floor drains. More particularly, it relates to a method for reducing the amount of Listeria in floor drains.
2. Background Art
Cleaning devices and formulations which are especially formulated for cleaning floor drains are known. For example, Ecolab Pathways Drain Ring available from Ecolab, Inc. in St. Paul, Minn.; CRS Power Strips available from Supply Systems of Dallas, Tex. and Spartan Chemical Consume Drop-In-A-Drain in Maumee, Ohio.
Listeria control is a critical issue for food retail customers. Listeria monocytogenes has three characteristics that make it a serious food safety concern. One of these characteristics is its ability to grow at refrigeration temperatures. Most food borne pathogens do not grow at all at refrigeration temperatures. Although Listeria grows slowly at low temperatures, it can grow to high levels given enough time. This means that just a few cells contaminating a food that will not be further cooked prior to eating it can, given enough time, grow to millions of cells, even if the food is kept refrigerated.
The second reason that Listeria is a food safety concern is that the organism is so common in the environment. It can be isolated from soil, plants, and many species of animals and birds. Because it is such a common organism, it is virtually impossible to keep Listeria out of a food retail setting where customers, employees, and equipment are moving in, out, and around the store throughout a day. If the organism finds its way into a niche where the environment is favorable and there is a source of food and water, it can colonize that location and grow to high levels. It is possible for the organism to then spread from that location to food contact surfaces like slicers, cutting boards, or hands and so contaminate food. It will grow at refrigeration temperatures and may be found in many locations in a retail setting. It takes a relatively high number of cells to have a high risk of causing disease so the key to controlling this disease is not to let the organism grow to high levels in the food or a food retail setting. One way of controlling this disease is by good cleaning programs.
The final reason that there is so much attention given to Listeria is that the disease it causes is very serious. The mortality rate for Listeriosis is approximately 20%–25%. Although Listeria generally causes a relatively minor illness that is often mistaken for the flu in healthy adults, in an individual that is immune compromised, the illness it causes can be far more serious. Immune compromised individuals are those whose immune systems are not fully functional. This can include the very young and very old, people that have other underlying illness like diabetes or cancer, pregnant women, or someone that is recovering from some surgical procedures such as a transplant. Immune compromised individuals are far more likely to develop complications from listeriosis like septicemia, meningitis, encephalitis, endocarditis, and spontaneous abortion. Many of the complications can result in death.
Given the nature of Listeria and the disease it causes, it is not surprising that retail customers are concerned about controlling this organism. Floor drains are a specific environment within a retail setting that is frequently cited as a potential reservoir for this organism. A floor drain provides a very favorable location for Listeria to grow. There is a lot of food and water present in most floor drains. Listeria can form biofilms that can attach to surfaces and many floor drains have very high surface areas. In many retail food stores, floor drains are cleaned infrequently so the organism has time to establish itself and grow to high levels.
Previous Studies
A study was conducted that examined floor drains and methods to control Listeria in them indicated that sanitizers may not be the best way to control pathogens in this environment. That study found that Listeria was present in approximately half of the drains tested. The level of Listeria was generally low, from one to two log10 colony forming unit (CFU). Aerobic Plate Counts (APCs) showed that the total level of microorganisms on the drains was from 4–8 log10 CFU. During this study two sanitizers were tested. A quat based sanitizer was tested at 200 and 400 PPM as well as a 10 PPM solution of chlorine dioxide. None of the tested sanitizers achieved much reduction. The chlorine dioxide was able to reduce but not eliminate the Listeria and the quat had a very small effect (ca. 0.3 to 0.5 reduction in log10 CFU).
The relatively poor performance of the sanitizers tested in this study was possibly the result of poor cleaning. Although the drains were cleaned with a degreaser that is used for general cleaning, there was still significant soil on the drains even after they were cleaned. The high soil level likely reduced the performance of the sanitizers tested in this study.
The prior art does not provide a floor drain cleaner which can effectively control Listeria. Neither does the prior art provide a floor drain cleaner of this type which is easily applied to the drain.
The objects of the invention therefore are:
a. Providing an improved floor drain cleaner.
b. Providing a floor drain cleaner which substantially reduces the presence of Listeria. 
c. Providing a floor drain cleaner of the foregoing type which is easily applied to a drain.
d. Providing a floor drain cleaner of the foregoing type which reduces the need to disassemble the drain and obviates contact with a drain.
e. Providing a floor drain cleaner of the foregoing type which provides competitive exclusion of bacteria in the drain.
f. Providing a floor drain cleaner of the foregoing type which is economical to use.